Lock.



,PATENTBD-0GT- 15, 1907. A. H. HARRIS.

LOCK. APPLICATION FILED JULYBO. 1908.

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ADOLPHUS Il. HARRIS, OF BIRMINGHAM, ALABAMA.

LOCK.

Speccation of Letters Patent.

Patented Oct. 15, 1907.

Application led July 30,1906. Serial N0. 328,381.

To all whom it may concern:

Be it known that l, ADoLPnUs H. HARRIS, a citizen of the United States, and a resident of Birmingham, in the county oi Jefferson and State of Alabama, have invented a new and useful Lock, of which the following is a specification.

My invention relates to locks. It provides a lock which is unusually secure from opening by unauthorized poisons.

The advantages and characteristics of the invention will hereafter appear in connection witha detailed description, reference being had to the accompanying drawing .which ill ustratesan exemplifying structure in which the invention is embodied.

Figure l is a froutiview from the outside of a door to which the lock is applied; Fig. 2, a sectional view looking froin the rear of Fig. l; Fig. 3, a side sectional view; and lfig. Ll. a detail sectional view showing the spring for the safety plate.

designates the` lock casing; 2, the usual plate on the outside of the door; 3, the knob; tl, the latch; 5, a crosspiece on the knob shaf t for withdrawing the latch', the bolt, in this instance having two jamb-engag-ing fingers 7 and 8; also being impelled toward engagement by spring or springs S), l0, a key slot in the bolt; ll., the main keyhole through which a key is inserted to withdraw the bolt in an obvious manner; l2, a safetyk plate, in this 'instance pivoted to the door plate at 13, and for purposes of artistic finish, iitted in a countersunk recess in said plate; lll, a prong on the safety plate extending through a slot in the door plate and into the lock easing; l5, a hook thereon, l7, a saiety bolt in the casing having a member 1S impelled to engage the hook l5 by a spring l5); 20, a spring conveniently set in a recessed part of the door plate and bearing against the safety plate; and 2l, a safety keyhole through which a key may be inserted to withdraw safety bolt l7; this keyhole is preferably covered by a swinging shield 22.

With the parts in the position shown in Fig. l, the door is hilly locked. The user of the lock is provided with two keys and preferably these are oi different style or size so that neither of them will operate both of the locks. l`o unlock the door, the cover 22 of the safety keyhole is swung aside, the safety key is inserted and turned withdrawing the safety bolt 17. This frees the hook l5 carried by the safety plate l2 and the plate springs outwardly under influence of spring 20 so that it may be conveniently grasped and raised still further, exposing the main keyhole ll. The main key is then inserted in this hole and the main bolt withdrawn, whereupon the door is free to be opened on turning the knob 3. ln closing and locking the door no key need be used since (5 is a spring bolt, and after the door is shut and locked by the main bolt the safety plate is simply pushed down and automatically locks in position. With the safety plate down and the door closed it is obvious that in order to open .the door, an unauthorized person must provide hi mself Vwith two duplicate keys or pick two locks since the main lock is guarded by another, and that the difficulties involved are such that improper opening of the door is almost impossible.

lt will be noted that a principal feature of the invention is the provision of a main lock and means controlled by a second lock preventing operation o the main lock until the second lock is properly operated upon. Many different embodiments of the invention may be made, but the drawing shows only one form. It may be e1nployed in connection with double acting locks, with those which are not spring actuated, with those in through the door and are screwedlinto the wood, or prof vided with machine screw threads and secured by nuts on the inside. By this construction it is practically impossible to remove the door plate from the outside. When these plates are improperly iastened the door may be frequently opened by removing the door plate and permittinglthe block to be forced away from the door.

Having described my invention, what I claim is:

ln a lock, the combination of a casing, a main lock operated by a removable key. an outer pivoted cover-plate controlling access to the keyhole of said main lock, and an lock operated by a different, removable key, for retaining the plate in closed position.

ln testimony whereof 1 have aflixed my signature in the presence of two witnesses.

ADOTJPHUS H. HARRIS.

Witnesses C. T. RANDALL, A. H. Aynns. 

